Dialysis machine, method of controlling the dialysis machine, and computer program for implementing the control

ABSTRACT

In an embodiment, a dialysis machine includes a dialyser, a fluid line in fluid communication with the dialyser, an inlet valve enabling fluid to flow into the fluid line towards the dialyser during a dialysis treatment, a disinfectant line connected to the fluid line via a disinfectant valve upstream of the dialyser, the disinfectant valve enabling a disinfectant fluid to be provided to at least part of the fluid line during a disinfection procedure, and a controller programmed to open the inlet valve, while the disinfectant line is connected to a source of disinfectant fluid, to create a positive pressure gradient across the disinfectant valve as fluid flows into the fluid line towards the dialyser, the positive pressure gradient ensuring that the disinfectant fluid from the source of disinfectant fluid does not leak into the fluid line during the dialysis treatment.

PRIORITY CLAIM

The present application is a continuation of U.S. application Ser. No.15/108,907, entitled, “Dialysis Machine, Method of Controlling theDialysis Machine, and Computer Program for Implementing the Control”,filed Jun. 29, 2016, which is a National Phase of InternationalApplication No. PCT/EP2014/078401, filed Dec. 18, 2014, which claimspriority to Swedish Patent Application No. 1351590-3, filed Dec. 30,2013, the entire contents of each of which are incorporated herein byreference and relied upon.

TECHNICAL FIELD

The present invention generally relates to a dialysis machine, a methodof controlling the dialysis machine, and a computer program forimplementing the control. In particular, the present invention relatesto providing disinfectant for disinfection of the dialysis machine.

BACKGROUND

Dialysis machines are routinely rinsed after each use an commonly aredisinfected at the end of the day. Disinfection may be using heat orbleach, and is often preceded by a vinegar rinse to remove carbonateencrustations and build-up in the tubing passages. Different usedsubstances used at disinfection are hereafter discussed using thegeneral term “disinfectant”.

During treatment using a dialysis machine, it is important thatdisinfectant does not reach the patient, and thus not the dialysis fluidduring treatment. A valve for letting disinfectant into a fluid circuitof the dialysis machine prevents this. However, as with all components,the valve may malfunction and provide some leakage. Thus, a valve onlycannot be relied on. Therefore, it is conventional that a disinfectantsource is disconnected before treatment commences, and that thedisinfectant intake connector is normally put in a connector parkingposition such that the dialysis machine by sensors, which senses thepresence of the disinfectant intake connector in the parking position,can ascertain that the operator has disconnected the disinfectantsource. The solution is of course safeguarding that no disinfectant canreach the fluid circuit during treatment, but, the operator is givenadditional manual tasks which is time consuming for the operator andthus less efficient in sense of labour resources. It is thereforedesired to provide a solution which decreases manual tasks for theoperator, but still safeguards that no disinfectant can reach the fluidcircuit during treatment.

SUMMARY OF THE INVENTION

An object of the invention is to at least alleviate the above statedproblem. The present invention is based on the understanding that avalve connected between a disinfectant source and the fluid circuit,although a malfunction of the valve giving some leakage occurs, will notprovide any disinfectant to the fluid circuit if connected at a positionin the fluid circuit where a pressure gradient is present duringtreatment taking any leaking disinfectant away from the rest of thefluid circuit. Instead, such leakage will be in the other direction,i.e. either the disinfectant may be more or less diluted by water, whichcauses significantly less harm since dilution of disinfectant may bedetected and the issue of leakage fixed or the disinfectant leak isprovided out from the circuit, e.g. via a pipe ending in free air, andno patient is exposed to the disinfectant. “Treatment” should here beconstrued generously, e.g. including parts of setup before a patient isconnected, such as priming, etc., where a patient may be exposed laterto substances introduced in the fluid circuit. The inventors have alsofound that this pressure gradient is provided between a positivepressure, e.g. provided by a pure water inlet of the dialysis machineand/or downstream pumps of the dialysis machine, and a lower pressurepresent in the disinfectant source and/or pipe(s) ending in free air.Thereby, the disinfectant source need not be disconnected by an operatorfrom the dialysis machine during treatment, whereby labour load may bedecreased.

According to a first aspect, there is provided a dialysis machinecomprising a fluid circuit for providing a dialysis fluid to a dialyser,wherein the fluid circuit comprises a tube with a first valve forproviding a disinfectant fluid for disinfecting at least a part of thefluid circuit at disinfection of the dialysis machine, characterised inthat the tube with the first valve is arranged to provide thedisinfectant fluid upstream the dialyser and at a position in the fluidcircuit where pressure is, during treatment, such that a pressuregradient between ports of the first valve is provided, the portscomprising at least a disinfectant fluid port and a fluid circuit port,such that the disinfectant fluid port of the first valve is enabled tobe safely connected to a source of disinfectant also during treatment.

The position for inserting the disinfectant may be downstream a pump forconcentrate distribution. The first valve may be a three-way valve witha first connection towards the source of disinfectant, a secondconnection towards the pump for concentrate distribution, and a thirdconnection towards the fluid circuit leading to the dialyser, and thefirst valve may be arranged to either connect the first and secondconnections, or the second and third connections for fluid flow.

The first valve may be a three-way valve with a first connection towardsthe source of disinfectant, a second connection towards the fluidcircuit, and a third connection towards atmospheric pressuresurroundings, and the first valve is arranged to either connect thefirst and second connections, or the first and third connections forfluid flow.

The fluid circuit may comprise an inlet for pure water, and the positionfor inserting the disinfectant may be downstream the inlet such that thepressure is always positive during treatment due to pressure of the purewater. The dialysis machine may further comprise a second valve arrangedupstream a point of the fluid circuit where the pure water is arrangedto mix with distributed concentrate such that, when the second valve isclosed during at least a part of the disinfection operation, a pump forconcentrate distribution may be enabled to suck up the disinfectant anddistribute the disinfectant into the fluid circuit. The second valve maybe a one-way valve.

The dialysis machine may further comprise a bypass coupling arranged toreceive dialyser fluid connection lines such that, at disinfectionoperation, the bypass coupling is employed to connect the dialysismachine upstream dialyser fluid path with the dialysis machinedownstream dialyser fluid path and to establish a connection to a purewater inlet. The first valve may be a three-way valve with a firstconnection towards the source of disinfectant, a second connectiontowards a tube in connection with the pure water inlet, and a thirdconnection towards the bypass coupling, and the valve may be arranged toeither connect the first and second connections, or the second and thirdconnections for fluid flow. The dialysis machine may further comprise athird valve being a three-way valve with a first connection towards thesecond connection of the first valve, a second connection towards a tubein connection with the pure water inlet, and a third connection towardsa concentrate connector of the machine, and the third valve may bearranged to either connect the second and third connections, or thefirst and third connections for fluid flow.

The dialysis machine may comprise a disinfectant selection valvearranged to enable selection of one of several disinfectant sources asthe source of disinfectant.

According to a second aspect, there is provided a method of controllinga fluid circuit for providing a dialysis fluid to a dialyser anddisinfection operation of a dialysis machine according to the firstaspect. The method comprises controlling the first valve to preventconnection of the disinfectant source to the fluid circuit duringtreatment; and controlling the first valve to connect the disinfectantsource to the fluid circuit during disinfection operation.

The position for inserting the disinfectant may be downstream a pump forconcentrate distribution and the first valve is a three-way valve with afirst connection towards the source of disinfectant, a second connectiontowards the pump for concentrate distribution, and a third connectiontowards the fluid circuit leading to the dialyser, and the first valvemay be arranged to either connect the first and second connections in afirst state, or the second and third connections for fluid flow in asecond state, wherein the method may comprise controlling the firstvalve to be in the first state and controlling the pump for concentratedistribution to provide fluid flow in a first direction duringdisinfection operation; and controlling the first valve to be in thesecond state and controlling the pump for concentrate distribution toprovide fluid flow in a second direction opposite to the first directionduring treatment.

The fluid circuit may comprise a bypass coupling arranged to receivedialyser fluid connection lines such that, at disinfection operation,the bypass coupling is employed to connect the dialysis machine upstreamdialyser fluid path with the dialysis machine downstream dialyser fluidpath and to establish a connection to a pure water inlet, the firstvalve may be a three-way valve with a first connection towards thesource of disinfectant, a second connection towards a tube in connectionwith the pure water inlet, and a third connection towards the bypasscoupling, wherein the method may comprise connecting at treatment thedialysis machine upstream dialyser fluid path and the dialysis machinedownstream dialyser fluid path, respectively, with the dialyser, andcontrolling the valve to connect the second and third connections forfluid flow; and at disinfection operation, connecting the dialysismachine upstream dialyser fluid path and the dialysis machine downstreamdialyser fluid path to the bypass coupling, and controlling the valve toconnect the first and second connections for fluid flow. The fluidcircuit may further comprise a third valve being a three-way valve witha first connection towards the second connection of the first valve, asecond connection towards a tube in connection with the pure waterinlet, and a third connection towards a concentrate connector of themachine, wherein the method may comprise, at treatment, controlling thethird valve to connect the second and third connections for fluid flow;and, at disinfection operation, controlling the third valve to connectthe first and third connections for fluid flow.

The dialysis machine may comprise a disinfection fluid tank arranged tointermediately store disinfection fluid and the disinfection fluid tankis connected to the second connection of the first valve. The dialysismachine may also comprise a coupling arrangement comprising a dialyserdownstream connector and a dialyser upstream connector, and the couplingarrangement is arranged to receive dialyser fluid connection lines suchthat, at disinfection operation, the coupling arrangement is employed toconnect the dialysis machine upstream dialyser fluid path with thedisinfection fluid tank to establish a connection to a pure water inlet,and the dialysis machine downstream dialyser fluid path to a drain lineof the dialysis machine via a fourth valve, wherein a first path and asecond path are formed at disinfection, wherein the first path comprisesa loop of the disinfection fluid tank via the first valve and a pathfrom the pure water inlet line to the dialyser upstream connector to thedisinfection fluid tank, and the second path comprises a loop of thedialyser downstream connector and a drainage pump via the fourth valveto the dialyser downstream connector, and when not performingdisinfection, the first and fourth valves are closed. The dialysismachine may comprise a bypass valve, wherein the bypass valve isarranged to provide disinfectant from the first path to the second path.

A disinfectant selection valve may be arranged to enable selection ofone of several disinfectants as the source of disinfectant, wherein themethod may comprise controlling the disinfectant selection valve atdisinfection operation according to a predetermined disinfection scheme.

According to a third aspect, there is provided a computer program, for acontroller of a dialysis machine, comprising computer program codeincluding computer executable instructions, which when downloaded andexecuted by a processor of the controller causes the controller tocontrol the dialysis machine to perform the method according to thesecond aspect.

Other objectives, features and advantages of the present invention willappear from the following detailed disclosure, from the attacheddependent claims as well as from the drawings. Generally, all terms usedin the claims are to be interpreted according to their ordinary meaningin the technical field, unless explicitly defined otherwise herein. Allreferences to “a/an/the [element, device, component, means, step, etc]”are to be interpreted openly as referring to at least one instance ofsaid element, device, component, means, step, etc., unless explicitlystated otherwise. The steps of any method disclosed herein do not haveto be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as additional objects, features and advantages of thepresent invention, will be better understood through the followingillustrative and non-limiting detailed description of preferredembodiments of the present invention, with reference to the appendeddrawings.

FIG. 1 schematically illustrates a dialysis machine with conventionalconnector arrangement for disinfectant.

FIGS. 2 to 9 schematically illustrate a dialysis machine with anarrangement for disinfectant according to embodiments, respectively.

FIG. 10 schematically illustrates a disinfectant source according to anembodiment.

FIG. 11 is a fluid scheme for explaining connections etc. of FIGS. 1 to10.

FIG. 12 is a flow chart schematically illustrating methods according toembodiments.

FIG. 13 schematically illustrates a computer-readable medium and aprocessor on which a computer program held by the computer-readablemedium can be executed.

FIGS. 14 and 15 schematically illustrate a dialysis machine with anarrangement for disinfection according to an embodiment.

DETAILED DESCRIPTION

The aim is to provide a solution which decreases manual tasks for theoperator, but still safeguards that no disinfectant can reach the fluidcircuit during treatment. A valve for letting disinfectant into a fluidcircuit of the dialysis machine prevents this. However, as with allcomponents, the valve may malfunction and provide some leakage. Thus, avalve only cannot be relied on. Therefore, as illustrated in FIG. 1, itis conventional that a disinfectant source is disconnected beforetreatment commences, and that the connector is normally put in aconnector parking position such that the dialysis machine by sensors,which senses the presence of the connector in the parking position, canascertain that the operator has disconnected the disinfectant source.The solution is of course safeguarding that no disinfectant can reachthe fluid circuit during treatment, but, the operator is givenadditional manual tasks which can be considered less efficient in senseof labour resources. It is therefore desired to provide a solution whichdecreases manual tasks for the operator, but still safeguards that nodisinfectant can reach the fluid circuit during treatment.

FIG. 1 schematically illustrates a dialysis machine 100 withconventional connector arrangement for disinfectant. It is to be notedthat elements, commonly present in a dialysis machine, but which are notof particular relevance for understanding the gist of this disclosure,are not depicted in detail. In the drawings, numerous of tubesinterconnect different elements. For the understanding of the schematicillustrations, FIG. 11 is first to be considered. FIG. 11 illustratestwo crossing tubes which are not interconnected, which is illustrated bythe “jump” at the position where they cross. Further, one of the tubesis branched. Thus A is connected with B, but there is no connectionbetween A or B to any of C, D or E. C and D are connected, and are alsoconnected to E. The illustrations should be readily understood fromthis.

A disinfectant connector 102 is arranged to either be connected to aconnector 103 for drawing disinfectant from a disinfectant source 104,or be connected to a parking position connector P for ensuring that thedisinfectant source 104 is disconnected from a fluid circuit of thedialysis machine 100. In FIG. 1, the disinfectant connector 102 is inits parking position P. The disinfectant connector 102 is connected viaa disinfectant valve 112 to the fluid circuit of the dialysis machine100.

The dialysis machine 100 comprises a pure water inlet which via a watervalve 116 and a water heater 118 provides water for preparing desiredfluids in the fluid circuit. The output of the water heater 118 isprovided to a connector A 109, to a three-way valve 114, which is alsoconnected to the disinfectant valve 112 and to a connector B 107, and toa position downstream a first concentrate pump A 120. The firstconcentrate pump A 120 is upstream connected to a connector 106 which isarranged to either be connected to the connector A 109, or to aconcentrate A connector 111 providing concentrate A from a concentratesource 108.

The connector B may be connected to a connector 107 which in turn isconnected via a tube towards a dry concentrate cartridge holder 122 andthe output of the dry concentrate holder is provided to a concentratepump B 124. The concentrate pump B 124 is thus able to draw concentratefrom the dry concentrate holder which is provided pure water via thethree-way valve 114.

Concentrate output from concentrate pump A 120 is mixed with pure waterdownstream the concentrate pump A 120, and the mix therefrom is furtherdownstream mixed with output from concentrate pump B 124. The mix formsthe dialysis fluid and is, for example by a flow pump 123 or by the purewater pressure, provided to a first connection 125 of a dialyser 126.Another flow pump 128 pumps the spent dialysis fluid from the dialyzer126 through the second connection 127 towards the drain. The flow pumps123 and 128 may be controlled such that an appropriate amount of wateris removed from the patient during treatment.

During disinfection, the disinfection valve 112 and three-way valve 114are set in position for letting disinfectant reach the fluid circuit ofthe dialysis machine. The disinfection connector 102 is also moved fromthe parking connector P to the connector 103 of the disinfectant source104. Here, it is to be noted that during disinfection operation, theconnector 106 is moved from connector 111 to a connector A 109, wherebyit can be seen that the corresponding concentrate pump A 120 can drawdisinfectant through the fluid circuit. It can also be noted that fluidconnection lines, which at treatment are connected to the dialyser 126,may at disinfection be disconnected from connectors 125, 127 of thedialyser 126 and be connected to a bypass connection 110, i.e. toconnectors 129, 130 of the bypass connection 110, which is employed toconnect the dialysis machine upstream dialyser fluid path with thedialysis machine downstream dialyser fluid path. The bypass connectionis also, via a valve 132, connected to a water line between the watervalve 116 and the heater 118 to establish a connection to the pure waterinlet. This enables disinfection of all parts of the fluid circuit.

FIGS. 2 to 6 schematically illustrate a dialysis machine with anarrangement for disinfectant according to embodiments, respectively. Theelements of the dialysis machine which does not have a direct impact onthe contribution of providing a solution which decreases manual tasksfor the operator, but still safeguards that no disinfectant can reachthe fluid circuit during treatment are shown as examples in FIGS. 2 to6, but other designs of the dialysis machine are equally feasible forthe principles of this disclosure, as will be readily understood fromthe description below. Further, these elements are not described furtherunless they have any impact on particular embodiments for the providingof a solution which decreases manual tasks for the operator, which stillsafeguards that no disinfectant can reach the fluid circuit duringtreatment.

The dialysis machine 200 of FIG. 2 provides a disinfectant source 204which is connected by a tube 203 for drawing disinfectant from adisinfectant source 204. For ensuring that the disinfectant source 204does not provide any disinfectant to a fluid circuit of the dialysismachine 200 when a patient is connected, the tube 203 is connected witha first valve 212 for providing the disinfectant fluid for disinfectingat least a part of the fluid circuit at disinfection of the dialysismachine, wherein the tube 203 with the first valve 212 is arranged toprovide the disinfectant fluid upstream a dialyser 226 and at a positionin the fluid circuit where pressure is, during treatment, such that apressure gradient between disinfectant fluid port and fluid circuit portof the first valve 212 is provided away from the fluid circuit.

The dialysis machine 200 comprises a pure water inlet which via a watervalve 216 and a water heater 218 provides water for preparing desiredfluids in the fluid circuit. The output of the water heater 218 isprovided to a connector A 209 and to a connector B 207, and to the firstvalve 212 at a position downstream a first concentrate pump A 220. Thefirst concentrate pump A 220 is upstream connected to a connector 206which is arranged to either be connected to the connector A 209, or to aconcentrate A connector 211 providing concentrate A from a concentratesource 208.

The connector B may be connected to a connector 207 which in turn isconnected via a tube towards a dry concentrate cartridge holder 222 andthe output of the dry concentrate holder is provided to a concentratepump B 224. The concentrate pump B 224 is thus able to draw concentratefrom the dry concentrate holder which is provided pure water via theconnector B 207.

Concentrate output from concentrate pump A 220 is mixed with pure waterdownstream the concentrate pump A 220 and the first valve 212, and themix therefrom is further downstream mixed with output from concentratepump B 224. The mix forms the dialysis fluid and is provided to a firstconnection 225 of a dialyser 226 wherein the fluid may be provided tothe dialyzer 226 by a pump 223 and is drawn through the dialyser 226 bya flow pump 228 and exits the dialyser 226 through a second connection227 thereof. The flow pumps 223 and 228 may be controlled such that anappropriate amount of water is removed from the patient duringtreatment. The dialysate, i.e. the spent dialysis fluid, is providedtowards a drain by the flow pump 228.

During disinfection, the disinfection valve 212 is set in position forletting disinfectant reach the fluid circuit of the dialysis machine.Disinfectant may be drawn through the fluid circuit by flow pump 223.Here, it is to be noted that during disinfection operation, theconnector 206 may be moved to the connector A 209, whereby it can beseen that the corresponding concentrate pump A 220 can draw disinfectantthrough parts of the fluid circuit. It can also be noted that fluidconnection lines, which at treatment are connected to the dialyser 226,may at disinfection be disconnected from connectors 225, 227 of thedialyser 226 and be connected to a bypass connection 210, i.e. toconnectors 229, 230 of the bypass connection 210, which is employed toconnect the dialysis machine upstream dialyser fluid path with thedialysis machine downstream dialyser fluid path. The bypass connectionis also, via a valve 232, connected to a water line between the watervalve 216 and the heater 218 to establish a connection to the pure waterinlet. This enables disinfection of all parts of the fluid circuit.

The first valve is arranged to provide the disinfectant fluid upstream adialyser 226 and at a position in the fluid circuit where pressure ispositive during treatment such that an inlet of the first valve isenabled to be safely connected to the disinfectant source 204 alsoduring treatment without any disinfectant being able to reach the fluidcircuit when a patient is connected. The position downstream the pump220 for concentrate distribution A provides a positive pressure from thewater which the concentrate is to be mixed with, and also due to thepump operation. The first valve 212 may be a three-way valve with afirst connection towards the disinfectant source 204 via the tube 203, asecond connection towards the pump 220 for concentrate distribution A,and a third connection towards the fluid circuit leading to the dialyser226. The three-way valve 212 may be arranged to connect the first andsecond connections, i.e. the disinfectant to the A pump, wherein the Apump may be driven to suck the disinfectant and provide it through theconnector A 206, which may be connected to connector 207, and therebyfurther through the fluid circuit during disinfection. The three-wayvalve 212 may also be arranged to connect the second and thirdconnections for fluid flow, i.e. the pump 220 to the part of the fluidcircuit which is downstream during treatment. Thus, during treatment,the pump 220 is driven in opposite direction to how it is driven duringdisinfection, whereby it inherently provides a positive pressure at theposition of the first valve 212 which in addition to the water pressureensures the effect. Thus, any leakage in the valve 212 provides a flowfrom the valve 212 towards the tube 203, and it is safeguarded that nodisinfectant will reach the fluid circuit during treatment if the valve212 is malfunctioning.

FIG. 3 illustrates a dialysis machine 300 similar to the ones depictedin FIGS. 1 and 2, but with an alternative embodiment of the position ofinserting the disinfectant. It is inherent that the water inlet providesa positive pressure, wherein the position provides similar properties asthe embodiment of FIG. 2. Thus, any leakage due to malfunctioning valve312 only causes dilution of the disinfectant by water which may leaktowards a disinfectant source 304.

The dialysis machine 300 of FIG. 3 provides a disinfectant source 304which is connected by a tube 303 for drawing disinfectant from adisinfectant source 304. For similar reasons as demonstrated withreference to FIG. 2, the tube 303 is connected with a first valve 312for providing the disinfectant fluid upstream a dialyser 326 and at aposition in the fluid circuit where pressure is, during treatment, suchthat a pressure gradient between disinfectant fluid port and fluidcircuit port of the first valve 312 is provided away from the fluidcircuit. The dialysis machine 300 comprises a pure water inlet which viaa water valve 316 and a water heater 318 provides water for preparingdesired fluids in the fluid circuit. The fluid circuit port of the firstvalve 312 is connected to the tube connection between the water valve316 and the water heater 318. The water pressure by the pure water willthus provide the pressure gradient. The output of the water heater 318is provided to a connector A 309 and to a connector B 307, and to aposition downstream a first concentrate pump A 320. The firstconcentrate pump A 320 is upstream connected to a connector 306 which isarranged to either be connected to the connector A 309, or to aconcentrate A connector 311 providing concentrate A from a concentratesource 308.

The connector B 307 may be connected via a tube towards a dryconcentrate cartridge holder 322 and the output of the dry concentrateholder is provided to a concentrate pump B 324. The concentrate pump B324 is thus able to draw concentrate from the dry concentrate holderwhich is provided pure water via the connector B 307.

Concentrate output from concentrate pump A 320 is mixed with pure waterdownstream the concentrate pump A 320, and the mix therefrom is furtherdownstream mixed with output from concentrate pump B 324. The mix formsthe dialysis fluid and is provided to a first connection 325 of adialyser 326 wherein the fluid may be provided to the dialyzer 326 by apump 323 and is drawn through the dialyser 326 by a flow pump 328 andexits the dialyser 326 through a second connection 327 thereof. The flowpumps 323 and 328 may be controlled such that an appropriate amount ofwater is removed from the patient during treatment. The dialysate, i.e.the spent dialysis fluid, is provided towards a drain by the flow pump328.

During disinfection, the disinfection valve 312 is set in position forletting disinfectant reach the fluid circuit of the dialysis machine.Disinfectant may be drawn through the fluid circuit by flow pump 323.Here, it is to be noted that during disinfection operation, theconnector 306 may be moved to the connector A 309, whereby it can beseen that the corresponding concentrate pump A 320 can draw disinfectantthrough parts of the fluid circuit. It can also be noted that fluidconnection lines, which at treatment are connected to the dialyser 326,may at disinfection be disconnected from connectors 325, 327 of thedialyser 326 and be connected to a bypass connection 310, i.e. toconnectors 329, 330 of the bypass connection 310, which is employed toconnect the dialysis machine upstream dialyser fluid path with thedialysis machine downstream dialyser fluid path. The bypass connectionis also, via a valve 332, connected to a water line between the watervalve 316 and the heater 318 to establish a connection to the pure waterinlet. This enables disinfection of all parts of the fluid circuit. Afurther advantage with the above demonstrated position for inserting thedisinfectant is that it enables using the heater for heating thedisinfectant for cases where the disinfectant is more efficient athigher temperatures.

The first valve is arranged to provide the disinfectant fluid upstreamthe dialyser 326 and at a position in the fluid circuit where pressureis positive during treatment such that an inlet of the first valve isenabled to be safely connected to the disinfectant source 304 alsoduring treatment without any disinfectant being able to reach the fluidcircuit when a patient is connected. The pure water inlet provides awater pressure during treatment that is higher than the pressureprovided from the tube 303. Thus, any leakage in the valve 312 providesa flow from the valve 312 towards the tube 303, and it is safeguardedthat no disinfectant will reach the fluid circuit during treatment ifthe valve 312 is malfunctioning.

FIG. 4 illustrates a dialysis machine 400 similar to the one depicted inFIG. 3, also in respect of the position for inserting the disinfectant.The features demonstrated with reference to FIG. 3 are thus applicablealso to FIG. 4, wherein the same reference numbers have been used whereapplicable. However, the embodiment of FIG. 4 also provides a secondvalve 313 which may be closed during a part of the disinfectionoperation, e.g. during the part of the disinfection when an amount ofdisinfectant is sucked from the disinfectant source 304, wherein theconcentrate pump or pumps may be used to suck the disinfectant viaconnectors A and/or B and distribute to the fluid circuit.

FIG. 5 illustrates a dialysis machine 500 similar to the ones depictedin FIGS. 1 and 2, but with an alternative embodiment of inserting thedisinfectant. The dialysis machine 500 of FIG. 5 provides a disinfectantsource 504 which is connected by a tube 503 for drawing disinfectantfrom a disinfectant source 504. For similar reasons as demonstrated withreference to FIG. 2, the tube 503 is connected with a first valve 512for providing the disinfectant fluid upstream a dialyser 526 and at aposition in the fluid circuit where pressure is, during treatment, suchthat a pressure gradient between disinfectant fluid port and fluidcircuit port of the first valve 512 is provided away from the fluidcircuit. The dialysis machine 500 comprises a pure water inlet which viaa water valve 516 and a water heater 518 provides water for preparingdesired fluids in the fluid circuit. It can also be noted that fluidconnection lines, which at treatment are connected to the dialyser 526,as demonstrated above, may at disinfection be disconnected fromconnectors 525, 527 of the dialyser 526 and be connected to a bypassconnection 510, i.e. to connectors 529, 530 of the bypass connection510, which is employed to connect the dialysis machine upstream dialyserfluid path with the dialysis machine downstream dialyser fluid path. Thebypass connection is also, via a valve 532, connected to the water linebetween the water valve 516 and the heater 518 to establish a connectionto the pure water inlet. This enables disinfection of all parts of thefluid circuit. An advantage with the above demonstrated position forinserting the disinfectant is that it enables using the heater forheating the disinfectant for cases where the disinfectant is moreefficient at higher temperatures.

The first valve 512 may comprise a three-way valve with a firstconnection towards the source of disinfectant 504, a second connectiontowards a tube in connection with the pure water inlet, i.e. via valve532, and a third connection towards the bypass coupling 510, and thefirst valve 512 is arranged to either connect the first and secondconnections wherein disinfectant may be enabled to reach the fluidcircuit, or the second and third connections for fluid flow wherein thebypass coupling may connect to the pure water inlet. The water pressureby the pure water will thus provide the pressure gradient at treatment.Furthermore, a pressure gradient is also provided towards the connectors529, 530 being exposed only to atmospheric pressure during treatment. Ifthe first valve 512 is malfunctioning, no disinfectant will reach thefluid circuit, and if a leak situation occurs, any fluid will leak outat the connectors 529, 530.

The output of the water heater 518 is provided to a connector A 509 andto a connector B 507, and to a position downstream a first concentratepump A 520. The first concentrate pump A 520 is upstream connected to aconnector 506 which is arranged to either be connected to the connectorA 509, or to a concentrate A connector 311 providing concentrate A froma concentrate source 508.

The connector B 507 may be connected via a tube towards a dryconcentrate cartridge holder 522 and the output of the dry concentrateholder is provided to a concentrate pump B 524. The concentrate pump B524 is thus able to draw concentrate from the dry concentrate holderwhich is provided pure water via the connector B 507.

Concentrate output from concentrate pump A 520 is mixed with pure waterdownstream the concentrate pump A 520, and the mix therefrom is furtherdownstream mixed with output from concentrate pump B 524. The mix formthe dialysis fluid and is provided to a first connection 525 of adialyser 526 wherein the fluid may be provided to the dialyzer 526 by apump 523 and is drawn through the dialyser 526 by a flow pump 328 andexits the dialyser 526 through a second connection 527 thereof. The flowpumps 523 and 528 may be controlled such that an appropriate amount ofwater is removed from the patient during treatment. The dialysate, i.e.the spent dialysis fluid, is provided towards a drain by the flow pump528.

During disinfection, the disinfection valve 512 is set in position forletting disinfectant reach the fluid circuit of the dialysis machine.Disinfectant may be drawn through the fluid circuit by the flow pump523. Here, it is to be noted that during disinfection operation, theconnector 506 may be moved to the connector A 509, whereby it can beseen that the corresponding concentrate pump A 520 can draw disinfectantthrough parts of the fluid circuit.

FIG. 6 illustrates a dialysis machine 600 similar to the one depicted inFIG. 5. The features demonstrated with reference to FIG. 5 are thusapplicable also to FIG. 6, wherein the same reference numbers have beenused where applicable. The dialysis machine 600 of FIG. 6 provides thepossibility of providing disinfectant also via a further valve 513connected to the first valve 512, wherein the concentrate pump or pumps520, 524 may be used to suck the disinfectant via connectors A and/or Band distribute to at least respective parts of the fluid circuit.Furthermore, a pressure gradient is also provided towards the connectors529, 530 being exposed only to atmospheric pressure during treatment. Ifthe first valve 512 is malfunctioning, no disinfectant will reach thefluid circuit, and if a leak situation occurs, any fluid will leak outat the connectors 529, 530.

FIG. 7 illustrates the dialysis machine 600 of FIG. 6 when set up fordisinfectant uptake. Here, it can be seen that the bypass coupling 510is used wherein the fluid circuit is disconnected from connectors 525,527 of the dialyser 526 and instead are connected to the connectors 529,530, respectively, of the bypass coupling 510. Further, it can be seenthat the disinfectant source 504 is connected via the tube 503, thefirst valve 512 and the further valve 513 to the connector A 509 and theconnector B 507 such that for example concentrate pump A 520 andconcentrate pump B 524 are enabled to suck disinfectant into the fluidcircuit.

FIG. 8 illustrates the dialysis machine 600 of FIG. 6 when set up fortreatment. Here, it can be seen that the dialyser 526 is connected tothe fluid circuit by connectors 525, 527, the pure inlet water isenabled to provide water through water valve 516 via the heater 518, thefurther valve 513 and to the connector B 507 and downstream concentratepump A 520 to enable operation as demonstrated above. The disinfectantsource 504 is connected to the connectors 529, 530 via the first valve512, wherein any disinfectant that may leak leaks through the connectors529, 530 and not into the fluid circuit.

FIG. 9 illustrates a dialysis machine 900 which provides a disinfectantsource 904 which is connected by a tube 903 for drawing disinfectantfrom a disinfectant source 904. For ensuring that the disinfectantsource 904 does not provide any disinfectant to a fluid circuit of thedialysis machine 900 when a patient is connected, the tube 903 isconnected with a first valve 912 for providing the disinfectant fluidfor disinfecting at least a part of the fluid circuit at disinfection ofthe dialysis machine, wherein the tube 903 with the first valve 912 isarranged to provide the disinfectant fluid upstream a dialyser 926. Thefirst valve 912 is a three-way valve with a first connection towards thesource of disinfectant 904, a second connection towards the fluidcircuit via a valve 914 with at similar function as the one 114demonstrated with reference to FIG. 1, and a third connection 913towards atmospheric pressure surroundings. The first valve is arrangedto either connect the first and second connections for enablingdisinfectant to the fluid circuit, or the first and third connectionswhen no disinfectant should reach the fluid circuit. Thereby, a pressuregradient between disinfectant fluid port and fluid circuit port of thefirst valve 912 is provided away from the fluid circuit. Thus, in thelatter state, the disinfectant source 904 is connected towards the thirdconnection 913 of the first valve 912, wherein any disinfectant that mayleak leaks through the third connection 913 and not into the fluidcircuit. As a further note to the solution where the first valve 912 hasa port towards atmospheric pressure, i.e. the surroundings, in casethere is a malfunction of the first valve 912 and there happen to be apressure below atmospheric pressure in the fluid circuit, e.g. due toany second error, the dialysis machine 900 will not suck in anydisinfectant since air will be sucked from the third connection 913because of the pressure gradient between atmospheric pressure and thepressure needed to suck the disinfectant from the disinfectant source914. The air will be detected and/or handled by the fluid circuit by itsinherent means for this. This principle is also relevant to theembodiments demonstrated above where the first valve has a connection tothe bypass connectors.

The dialysis machine 900 comprises a pure water inlet which via a watervalve 916 and a water heater 918 provides water for preparing desiredfluids in the fluid circuit. The output of the water heater 918 isprovided to a connector A 909, to a connector B 907 via the valve 914,and at a position downstream a first concentrate pump A 920. The firstconcentrate pump A 920 is upstream connected to a connector 906 which isarranged to either be connected to the connector A 909, or to aconcentrate A connector 911 providing concentrate A from a concentratesource 908.

The connector B may be connected to a connector 907 which in turn isconnected via a tube towards a dry concentrate cartridge holder 922 andthe output of the dry concentrate holder is provided to a concentratepump B 924. The concentrate pump B 924 is thus able to draw concentratefrom the dry concentrate holder which is provided pure water via theconnector B 907.

Concentrate output from concentrate pump A 920 is mixed with pure waterdownstream the concentrate pump A 920, and the mix therefrom is furtherdownstream mixed with output from concentrate pump B 924. The mix formsthe dialysis fluid and is provided to a first connection 925 of thedialyser 926 wherein the fluid may be provided to the dialyzer 926 by apump 923 and is drawn through the dialyser 926 by a flow pump 928 andexits the dialyser 926 through a second connection 927 thereof. The flowpumps 923 and 928 may be controlled such that an appropriate amount ofwater is removed from the patient during treatment. The dialysate, i.e.the spent dialysis fluid, is provided towards a drain by the flow pump928.

During disinfection, the disinfection valve 912 is set in position forletting disinfectant reach the fluid circuit of the dialysis machine.Here, it is to be noted that during disinfection operation, theconnector 906 may be moved to the connector A 909, whereby it can beseen that the corresponding concentrate pump A 920 can draw disinfectantthrough the fluid circuit. It can also be noted that fluid connectionlines, which at treatment are connected to the dialyser 926, may atdisinfection be disconnected from connectors 925, 927 of the dialyser926 and be connected to a bypass connection 910, i.e. to connectors 929,930 of the bypass connection 910, which is employed to connect thedialysis machine upstream dialyser fluid path with the dialysis machinedownstream dialyser fluid path. The bypass connection is also, via avalve 932, connected to a water line between the water valve 916 and theheater 918 to establish a connection to the pure water inlet. Thisenables disinfection of all parts of the fluid circuit.

FIGS. 14 and 15 schematically illustrate a dialysis machine 1400 with anarrangement for disinfectant according to an embodiment. FIG. 14illustrates the machine 1400 arranged for treatment, and FIG. 15illustrates the machine 1400 arranged for disinfection. The dialysismachine 1400 provides a disinfectant source 1404 which is connected by atube 1403 for drawing disinfectant from the disinfectant source 1404. Adisinfection tank 1419 is provided for loading the machine 1400 withdisinfectant for the next disinfection procedure. This is performed byopening a valve 1417, preferably at the end of one disinfection session,and filling-up the disinfectant tank 1419 from the disinfectant source.

For similar reasons as demonstrated with reference to FIG. 5, the tube1403 is connected with a first valve 1412 for providing the disinfectantfluid upstream a dialyser 1426 and at a position in the fluid circuitwhere pressure is, during treatment, such that a pressure gradientbetween disinfectant fluid port and fluid circuit port of the firstvalve 1412 is provided away from the fluid circuit. It is to be notedthat during treatment, the dialysis machine 1400 comprises a pure waterinlet which via a water valve 1416 and a water heater 1418 provideswater for preparing desired fluids in the fluid circuit. It can also benoted that fluid connection lines, which at treatment are connected tothe dialyser 1426, as demonstrated above, may at disinfection bedisconnected from connectors 1425, 1427 of the dialyser 1426 and beconnected to the connectors 1429 and 1430, among which the connector1430 is employed to connect the dialysis machine upstream dialyser fluidpath with the disinfection fluid tank 1419 to establish a connection tothe pure water inlet path, and the connector 1429 is employed to connectthe dialysis machine downstream dialyser fluid path to a drain line ofthe dialysis machine via a fourth valve 1415. Thus, a first path and asecond path are formed at disinfection, where the first path comprisesthe parts upstream the dialyser at treatment, which may be considered asthe “clean side” of the machine since no spent dialysate should bepresent there, and the second path comprises the parts downstream thedialyser at treatment.

The first path thus comprises a loop of the disinfection fluid tank 1419via the first valve 1412 and a path from the pure water inlet line tothe dialyser upstream connector 1430 to the disinfection fluid tank 1419again. This enables disinfection of all parts of the fluid circuitupstream the dialyser. The second path comprises a loop of the dialyserdownstream connector 1429 and a drainage pump 1428 via the fourth valve1415 to the dialyser downstream connector 1429 again. The disinfectantmay be provided to the loop of the second path through a bypass valve,e.g. one normally present in dialysis apparatuses prior to the dialyser1426 and normally having the function to short-circuit the flow to passthe dialyser 1426 towards the drain in case the dialysate is found, e.g.by measurements, to be unsuitable to be sent to the dialyser 1426. Thatbypass valve may in the above demonstrated structure be used to providedisinfectant from the first path to the second path. Alternatively, thedisinfectant is provided through a fifth valve 1432, as illustrated asan option in FIGS. 14 and 15. The fifth valve 1432 may be controlledtogether with the fourth valve 1415 such that the drainage pump 1428 isenabled to suck up the disinfectant. The fifth valve 1432 mayalternatively be a one-way valve. However, other bypass valvearrangements for providing the disinfectant to that loop are equallyfeasible, such as a one-way valve between the tube at the connector 1430and the tube at connector 1429, a branch of the tube 1403 connected tothe loop of the second path with a valve arrangement to the second path,for example to the input of the drainage pump 1428, etc. This enablesdisinfection of all parts of the fluid circuit downstream the dialyser.When not performing disinfection, the first and fourth valves 1412, 1415are closed. The fifth valve 1432 in the option given above may be openduring treatment such that any leakage is provided to the connector1429.

This enables disinfection of all parts of the fluid circuit bothupstream and downstream the dialyser.

The water pressure by the pure water will thus provide the pressuregradient at treatment. Furthermore, a pressure gradient is also providedtowards the connector 1430 being exposed only to atmospheric pressureduring treatment. If the first valve 1412 is malfunctioning, nodisinfectant will reach the fluid circuit, and if a leak situationoccurs, any fluid will leak into the disinfectant tank 1419 and out atthe connector 1430.

The output of the water heater 1418 is provided to a connector A 1409and to a connector B 1407, and to a position downstream a firstconcentrate pump A 1420. The first concentrate pump A 1420 is upstreamconnected to a connector 1406 which is arranged to either be connectedto the connector A 1409, or to a concentrate A connector 1411 providingconcentrate A from a concentrate source 1408.

The connector B 1407 may be connected via a tube towards a dryconcentrate cartridge holder 1422 and the output of the dry concentrateholder is provided to a concentrate pump B 1424. The concentrate pump B1424 is thus able to draw concentrate from the dry concentrate holderwhich is provided pure water via the connector B 1407.

Concentrate output from concentrate pump A 1420 is mixed with pure waterdownstream the concentrate pump A 1420, and the mix therefrom is furtherdownstream mixed with output from concentrate pump B 1424. The mix formsthe dialysis fluid and is provided to a first connection 1425 of adialyser 1426 wherein the fluid may be pumped through the dialyser 1426by a flow pump 1423 and/or drawn through the dialyser 1426 by a flowpump 1428 and exits the dialyser 1426 through a second connection 1427thereof. The flow pumps 1423 and 1428 may be controlled such that anappropriate amount of water is removed from the patient duringtreatment. The dialysate, i.e. the spent dialysis fluid, is providedtowards a drain by the flow pump 1428.

During disinfection, the disinfection valve 1412 is set in position forletting disinfectant reach the fluid circuit of the dialysis machine.Here, it is to be noted that during disinfection operation, theconnector 1406 may be moved to the connector A 1409, whereby it can beseen that the corresponding concentrate pump A 1420 can drawdisinfectant through parts of the fluid circuit, i.e. the branch of pumpA 1420. Similar applies for pump B 1424 and the branch of pump B 1424.This enables disinfection of all parts of the fluid circuit.

FIG. 10 illustrates a disinfectant source 1000 according to anembodiment. In the embodiments of dialysis apparatuses above, a singlesource of disinfectant has been illustrated. This single source ofdisinfectant may be substituted by a multiple source of disinfectant,e.g. as demonstrated with reference to FIG. 10. The disinfectant sourcecomprises a first source of disinfectant 1002 and a second source ofdisinfectant 1004. Each of the sources of disinfectant 1002, 1004 isconnected to a port of a disinfectant selection valve 1006,respectively, wherein the valve is arranged to select the port to drawdisinfectant from to provide to an output 1008 of the disinfectantsource 1000. Embodiments with three or more sources of disinfectants arealso possible.

FIG. 12 is a flow chart schematically illustrating methods according toembodiments. The methods relate to controlling a fluid circuit forproviding a dialysis fluid to a dialyser and disinfection operation of adialysis machine according to what is demonstrated above with referenceto any of FIGS. 2 to 9, 14 and 15, and also their application with adisinfectant source as demonstrated with reference to FIG. 10. It isdetermined in 1200 whether the dialysis machine is to operate indisinfection operation mode or in treatment operation mode. The methodcomprises controlling 1202 the first valve to prevent connection of thedisinfectant source to the fluid circuit during treatment; andcontrolling 1201 the first valve to connect the disinfectant source tothe fluid circuit during disinfection operation.

According to an embodiment the method comprises controlling 1203 thefirst valve to be in the first state and controlling 1205 the pump forconcentrate distribution to provide fluid flow in a first directionduring disinfection operation. For treatment operation, the methodcomprises controlling 1204 the first valve to be in the second state andcontrolling 1206 the pump for concentrate distribution to provide fluidflow in a second direction opposite to the first direction duringtreatment. This is for example applicable where the position isdownstream a pump for concentrate distribution and the first valve is athree-way valve with a first connection towards the source ofdisinfectant, a second connection towards the pump for concentratedistribution, and a third connection towards the fluid circuit leadingto the dialyser, and the first valve may be arranged to either connectthe first and second connections in a first state, or the second andthird connections for fluid flow in a second state.

For an embodiment where the fluid circuit comprises a bypass coupling asa receiving part for the dialyser connection lines of the dialysismachine as demonstrated above, the method may have an embodiment thatcomprises, at treatment, connecting 1210 the dialyser with the dialysismachine upstream dialyser fluid path and the dialysis machine downstreamdialyser fluid path, respectively, and controlling 1202 the valve toconnect the second and third connections for fluid flow; and atdisinfection operation, connecting 1209 to the bypass coupling, i.e. thedialysis machine upstream dialyser fluid path and the dialysis machinedownstream dialyser fluid path, to bypass the dialyser, and controlling1201 the valve to connect the first and third connections for fluidflow. The fluid circuit may further comprise a third valve being athree-way valve with a first connection towards the second connection ofthe first valve, a second connection towards a tube in connection withthe pure water inlet, and a third connection towards a concentrateconnector of the machine. In such an embodiment, the method maycomprise, at treatment, controlling 1212 the third valve to connect thesecond and third connections for fluid flow; and, at disinfectionoperation, controlling 1211 the third valve to connect the first andthird connections for fluid flow.

A disinfectant selection valve may be arranged to enable selection ofone of several disinfectants as the source of disinfectant. This can bedone for the entire disinfection process, or a more complex sequence orscheme of disinfection operations with use of more than onedisinfectant, e.g. in sequence, can be employed. The method may thuscomprise controlling 1213 the disinfectant selection valve atdisinfection operation according to a predetermined disinfection scheme.

The methods according to the present invention are suitable forimplementation with aid of processing means, such as computers and/orprocessors, especially for the case where the dialysis machine iscomputer controlled. Therefore, there is provided computer programs,comprising instructions arranged to cause the processing means,processor, or computer to perform the steps of any of the methodsaccording to any of the embodiments described with reference to FIG. 12.The computer programs preferably comprises program code which is storedon a computer readable medium 1300, as illustrated in FIG. 13, which canbe loaded and executed by a processing means, processor, or computer1302 to cause it to perform the methods, respectively, according toembodiments of the present invention, preferably as any of theembodiments described with reference to FIG. 12. The computer 1302 andcomputer program product 1300 can be arranged to execute the programcode sequentially where actions of any of the methods are performedstepwise. The processing means, processor, or computer 1302 ispreferably what normally is referred to as an embedded system. Thus, thedepicted computer readable medium 1300 and computer 1302 in FIG. 13should be construed to be for illustrative purposes only to provideunderstanding of the principle, and not to be construed as any directillustration of the elements.

The invention has mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled inthe art, other embodiments than the ones disclosed above are equallypossible within the scope of the invention, as defined by the appendedpatent claims.

1. A dialysis machine comprising: a dialyser; a fluid line in fluidcommunication with the dialyser; an inlet valve configured to enablefluid to flow into the fluid line towards the dialyser during a dialysistreatment; a disinfectant line connected to the fluid line via adisinfectant valve upstream of the dialyser, the disinfectant valveenabling a disinfectant fluid to be provided to at least part of thefluid line during a disinfection procedure; and a controller programmedto open the inlet valve, while the disinfectant line is connected to asource of disinfectant fluid, to create a positive pressure gradientacross the disinfectant valve as fluid flows into the fluid line towardsthe dialyser, the positive pressure gradient ensuring that thedisinfectant fluid from the source of disinfectant fluid does not leakinto the fluid line during the dialysis treatment.
 2. The dialysismachine of claim 1, wherein the fluid is water.
 3. The dialysis machineof claim 2, wherein the controller is programmed to cause the water tomix with concentrate to create dialysis fluid after the water passes aposition of the disinfectant valve along the fluid line.
 4. The dialysismachine of claim 2, wherein the disinfectant valve is connected to thefluid line downstream of a pump configured to pump concentrate to bemixed with the water to create dialysis fluid.
 5. The dialysis machineof claim 1, wherein the fluid is dialysis fluid.
 6. The dialysis machineof claim 1, which includes a pump configured to pump dialysis fluidthrough the fluid line towards the dialyser during the dialysistreatment, wherein the controller is programmed to use the pump to pumpdisinfectant fluid from the source of disinfectant fluid through thefluid line during the disinfection procedure.
 7. The dialysis machine ofclaim 6, wherein the disinfectant valve is connected to the fluid lineupstream of the pump.
 8. A dialysis machine comprising: a dialyser; afluid line in fluid communication with the dialyser; a pump configuredto cause an amount of water to be removed from the patient during adialysis treatment; an inlet valve configured to enable fluid to flowinto the fluid line towards the dialyser during the dialysis treatment;a disinfectant line connected to the fluid line via a disinfectant valveupstream of the pump, the disinfectant valve enabling a disinfectantfluid to be provided to at least part of the fluid line during adisinfection procedure; and a controller programmed to open the inletvalve, while the disinfectant line is connected to a source ofdisinfectant fluid, to create a positive pressure gradient across thedisinfectant valve as fluid flows into the fluid line towards thedialyser, the positive pressure gradient ensuring that the disinfectantfluid from the source of disinfectant fluid does not leak into the fluidline during the dialysis treatment.
 9. The dialysis machine of claim 8,wherein the pump is positioned upstream of the dialyser.
 10. Thedialysis machine of claim 8, wherein the pump is positioned downstreamof the dialyser.
 11. The dialysis machine of claim 8, wherein the pumpis configured to pump fresh dialysis fluid towards the dialyser duringthe dialysis treatment.
 12. The dialysis machine of claim 8, wherein thepump is configured to pump spent dialysis fluid from the dialyser duringthe dialysis treatment.
 13. The dialysis machine of claim 8, wherein thecontroller is programmed to use the pump to pump disinfectant fluid fromthe source of disinfectant fluid through the fluid line during thedisinfection procedure.
 14. A method of controlling a dialysis machine,the method comprising: connecting a disinfectant line to a fluid linevia a disinfectant valve upstream of a dialyser, the disinfectant valveenabling a disinfectant fluid to be provided to at least part of thefluid line during a disinfection procedure, the fluid line enablingfluid to flow towards the dialyser during a dialysis treatment; andopening an inlet valve to the fluid line, while the disinfectant line isconnected to a source of disinfectant fluid, to create a positivepressure gradient across the disinfectant valve as fluid flows into thefluid line towards the dialyser, the positive pressure gradient ensuringthat the disinfectant fluid from the source of disinfectant fluid doesnot leak into the fluid line during the dialysis treatment.
 15. Themethod of claim 14, wherein the fluid is water.
 16. The method of claim15, which includes causing the water to mix with concentrate to createdialysis fluid after the water passes a position of the disinfectantvalve along the fluid line.
 17. The method of claim 15, which includesconnecting the disinfectant valve to the fluid line downstream of a pumpconfigured to pump concentrate to be mixed with the water to createdialysis fluid.
 18. The method of claim 14, wherein the fluid isdialysis fluid.
 19. The method of claim 14, which includes operating apump to pump dialysis fluid through the fluid line towards the dialyserduring the dialysis treatment, and which includes operating the pump topump disinfectant fluid from the source of disinfectant fluid throughthe fluid line during the disinfection procedure.
 20. The method ofclaim 19, which includes connecting the disinfectant valve to the fluidline upstream of the pump.
 21. The method of claim 14, which includesopening a tank valve, which connects the source of disinfectant fluid toa disinfection tank, to fill the disinfection tank from the source ofdisinfectant fluid, thereby loading the disinfection tank for a nextdisinfection procedure.
 22. The method of claim 21, wherein opening thetank valve to fill the disinfection tank from the source of disinfectantfluid is performed at the end of one disinfection procedure.
 23. Themethod of claim 21, further comprising: fluidly connecting thedisinfection tank upstream of the dialyser to establish a fluidconnection between the disinfection tank and a pure water inlet; andfluidly connecting a drain line downstream of the dialyser.